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Asymptomatic bacteriuria

Definition

Asymptomatic bacteriuria is a significant number of bacteria in the urine that occurs without any of the usual symptoms (burning during urination or increased frequency of urination). Asympomatic bacteruria may not need treatment, which makes it different from a bacterial urinary tract infection.

Causes, incidence, and risk factors

Asymptomatic bacteriuria occurs in up to 6% of healthy individuals. It affects 18% of people with diabetes (mostly women), and 20% of elderly individuals (more often women than men). The reasons for the lack of symptoms are not well understood.

Most patients with asymptomatic bacteriuria do not need treatment because the bacteria isn't causing any harm. However, certain groups are at a higher risk for kidney infections if they develop asymptomatic bacteriuria. Those at risk include:

• People with diabetes
• Elderly people
• Pregnant women -- if asymptomatic bacteriuria is left untreated, up to 40% will develop a kidney infection.
• Kidney transplant patients
• Young children with vesicoureteral reflux
• Patients with infected kidney stones

Symptoms

By definition, asymptomatic bacteriuria causes no symptoms. The symptoms of a urinary tract infection include burning during urination, an increased urgency to urinate, and increased frequency of urination.

Signs and tests

Asymptomatic bacteriuria is detected by the discovery of significant bacterial growth in a urine culture taken from a urine sample.

Treatment

Not all patients with asymptomatic bacteriuria respond to treatment or even need treatment. Pregnant women, kidney transplant recipients, children with vesicoureteral reflux, and people with infected kidney stones appear to be more likely to benefit from treatment with antibiotics.

In addition, if asymptomatic bacteriuria is found prior to a urological procedure, it should be treated to prevent complications of the procedure. The course of treatment in these cases depends on the person's risk factors.

Expectations (prognosis)

Most individuals with asymptomatic bacteriuria who do not have risk factors for complications do extremely well, and do not have any increased rates of symptomatic infections or decrease in kidney function.

The prognosis for treatment in the high-risk group category is good if the infection is detected early, but the outlook depends on the person's underlying conditions or illnesses.

Complications

Individuals in high-risk groups have a significant risk of progressing to a true kidney infection if the bacteriuria is not treated. In certain cases, such as renal transplant recipients, kidney infection may lead to loss of kidney function.

Calling your health care provider

If you have been told you have asymptomatic bacteriuria and you are in a high-risk group for complications, notify your health care provider. Also, if you begin to develop fever, have difficulty emptying your bladder, feel pain with urination, or have flank or back pain -- notify your health care provider. You will need to be evaluated for a bladder or kidney infection.

Review Date:5/26/2006
Reviewed By:Monica Gandhi MD, MPH, Assistant Professor, Division of Infectious Diseases, UCSF, San Francisco, CA. Review provided by VeriMed Healthcare Network.

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